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ODVA EtherNet/IP

This describes the functionality of the ODVA EtherNet/IP VIM Firmware (IOD-4116). This firmware supports all of the features of Generic EtherNet/IP, in addition to new messaging modes, redundancy, and DeviceNet IO card emulation.

Protocol Compatibility

The Generic EtherNet/IP firmware implements the protocol as specified in the following documents:

These documents are published by Rockwell.

Theory of Operation

The DeltaV Virtual I/O Module (VIM), together with its dedicated system power supply must be plugged into a 2-module carrier on the left-hand side of the DeltaV controller as shown below. The card is clearly labeled with the interface type as Virtual I/O Module. LEDs, located on the front of the card, show the power, error, and port status of the interface at a glance. This current version of the VIM firmware supports both simplex and redundant communications with field devices.

The VIM provides a native DeltaV I/O interface to open plant Ethernet networks and devices that use the EtherNet/IP protocol. DeltaV controllers can read and write signals from the plant floor devices that use these Ethernet networks such as PLCs, Motor Control Centers, and Weigh Scales. As such, the VIM is a Network Gateway between DeltaV controllers and field devices supporting network communications. Simplex and Redundant connectivity is illustrated below:

Figure 1 - Simplex EtherNet/IP Network

Figure 2 - Redundant EtherNet/IP Network

Hardware Requirements

The ODVA EtherNet/IP firmware is only supported on the VIM2 hardware platform. For EtherNet/IP support on the VIM1 hardware platform, use the Generic EtherNet/IP firmware.

Software Requirements

The ODVA EtherNet/IP firmware can only be configured using VIMNet Explorer version 9.3 or later. Earlier version are not supported with this firmware.


As of version 1.3, the ODVA EtherNet/IP firmware supports VIM redundancy. See ODVA EtherNet/IP Redundant Communications for details.

Messaging Support

This firmware provides the following compatible functions using the Control and Information Protocol (CIP) as defined in release 1.0 of the EtherNet/IP specification from Open DeviceNet Vendor Assoc. (ODVA) & ControlNet International.

  1. Connected implicit messaging

    This creates an I/O connection between the device and the VIM for fast, periodic data exchange. It uses transport class 1 for the data format. Data is read or written from Assembly instances in the field device.

  2. Unconnected explicit messaging (UCMM)

    These messages are initiated from the VIM, in a request / response format.

  3. Connected explicit messaging (Class 3)

    These messages are initiated from the VIM, in a request / response format. The VIM will initiate a CIP connection to the configured CIP class instance, then send messages through that connection.

The type of messaging used is application dependent. In some cases, an application may have a mixture of all types within the same system.

DeltaV Native I/O

The VIM provides a native DeltaV I/O interface by emulating four DeltaV IO cards. The IO cards may be any combination of Programmable Serial Interface Cards (PSICs) or DeviceNet Interface Cards (DNIC). By design, the VIM acquires the last 8-wide I/O carrier of a DeltaV system, emulating cards 57-60 or 61-64 as a single, simplex unit. Installing 2 simplex VIMs side-by-side provides emulation of all 8 serial I/O cards 57-64. The configuration of card group 57-60 or 61-64, and network properties of connected field devices is done in the VIMNet Explorer described in Configure Simplex EtherNet/IP Communications.

The emulated cards appear to DeltaV as real I/O. The configuration of data tables to be read and written is done in VIMNet Explorer and DeltaV Explorer. This allows communications with any PLC or non-PLC device that supports the EtherNet/IP messaging.

Each PSIC has 2 ports configured under it. There are 16 datasets under each port. Consequently, the VIM has the capacity of 128 datasets. One dataset is equivalent to 100 16-bit registers, or 50 floating point (32 bit) registers. These 128 datasets are user mapped to PLC devices as required for your application.

Each DNIC has 1 port that allows up to 61 devices to be configured. Each device may have two buffers, one for input and one for output. The maximum size of a buffer in DeltaV is 256 bytes. Those buffers may be split into any combination of signals with varying data types. A single device supports 255 signals. The signals can be any combination of input or output signals.

IO Devices

The DeltaV device address is considered unique in the IO card's port. Specifically, within a given port, all configured devices are unique. The user can, however, configure the same device with the same address under another port. For a device address configured more than once under more than one port, the IP address always remains unique.

The VIMNet Explorer configuration correlates each unique PLC device address with an IP address. At the simplest level, each PLC device equates to an IP address. In some cases, a single IP address may also be mapped to more than one PLC device, as is typically required when interfacing with Motor Control Centers or when using an Ethernet to serial gateway device. In this case, the IP address mapped belongs to a gateway device, which in turn acts as a data concentrator communicating serially with multiple actual PLC devices, each with a unique address.

The VIM has the capacity to communicate with up to 128 network devices simultaneously. Messages for each DeltaV device are concurrently handled by the VIM, thus increasing throughput. The timing of a single device does not normally affect the other devices. This is particularly useful when a single device has errors, or has a high response time. The exception to this is when using an Ethernet to serial gateway device. One of the serial devices has the potential to slow down all the other serial devices on that gateway.